OVERVIEW

ADDRESS: c/o Cryptologia, Rose-Huiman Institute of Technology, Terre Haute IN 47803 USA.

ABSTRACT: The Ultra background is given to some operations by U. S. Navy escort carriers against U-boats in 1943 and 1944.

KEYWORDS: Enigma, Ultra, Kriegsmarine, U-boats, refueling, U-tanker, escort carriers, F-211, Op-20-G, Bletchley Park, OIC, Winn, Knowles.

This article describes the complex intelligence background to some operations in World War II against the U-boats by the United States Navy escort carrier (CVE) task groups, and the catastrophic results for the U-boat fleet, especially the U-boat tankers. The operations show a significant difference of approach in the way in which the United States and British naval authorities employed Ultra (or special intelligence) from naval Enigma - and escort carriers. ^[2]

By the end of May 1943, the tide had turned in the Battle of the Atlantic. A devastating combination of centimetric radar, shipborne high frequency direction finding (HF/DF), very long range aircraft, new weaponry and, above all, the efforts of Allied seamen and airmen had inflicted catastrophic losses on the U-boats. Intelligence from Enigma probably did not affect the losses much, since it was still being employed only to guide convoys past the U-boats, and not offensively. No fewer than 39 U-boats had been sunk in May out of a total operational fleet (that is, excluding boats undergoing trials and training) of about 235. Admiral Karl D nitz, the Kriegsmarine's Admiral Commanding U-boats (Befehlshaber der U-boote, or BdU) ruefully noted in his war diary that the...